TITLE:
Comprehensive Genetic Analysis by Integration of Conventional Karyotyping and Interphase FISH Helps Refinement of Biological Subclasses with Clinical Impact in Chronic Lymphocytic Leukemia
AUTHORS:
P. S. Kadam Amare, S. Kakade, K. Chopra, M. Sengar, H. Menon, H. Jain, B. Bagal, P. G. Subramanian, S. Gujral
KEYWORDS:
CLL, FISH, Complex Karyotype, Biological Subclasses, Prognostic Groups
JOURNAL NAME:
Journal of Cancer Therapy,
Vol.7 No.6,
June
23,
2016
ABSTRACT: Background: Various
genetic technologies have been employed in the identification of genomic
complexity and refinement of prognostic classification of clinically
heterogeneous disease of chronic lymphocytic leukemia (CLL). Objective: The
present study of interphase cytogenetics and conventional karyotyping was
undertaken to perform comprehensive analysis of CLL genetics with an approach
to refine early prognostication of disease. Material & Methods:
Retrospective analysis by fluorescence in
situ hybridization (FISH) was carried out on total 671 patients of CLL at
diagnosis between 2008 and 2015. Conventional cytogenetics studies were
performed in 50 of 671 patients using CPG Oligonucleotide + IL-2 and TPA (12-O-Tetradecanyl
Phorbol 13-acetate) for stimulation of lymphocytes cultures. Results:
Interphase cytogenetics could detect recurrent abnormalities such as
del(13q14), +12, del(17p13), del(11q22), del(6q23) in 71% of cases. The incidence
of del(13q) was higher in Rai stage 0, I, II (p = 0.0005); whereas patients
with ≥2 aberrations were more common in advance stage III, IV (p = 0.001).
Frequency of IgH translocation was 7%. Morphology and immunophenotypic analysis
revealed atypical CLL with higher frequency of t(14;19) than t(14;18).
Conventional karyotype could detect abnormal karyotype in 97% of cases which
displayed targeted FISH abnormalities along with additional non-targeted
chromosomal abnormalities. Patients with negative FISH markers showed clonal
non-recurrent numerical and structural changes. The complex karyotype was
identified in 24% cases which included targeted FISH aberrations as well as
non-targeted numerical and structural abnormalities like deletions, and
unbalanced translocations. A significant association was observed between
complex karyotype and coexistence of ≥2 FISH markers (p = 0.009) and del(11q22)
&/or del(17p) (p = 0.03). Conclusion: Our data of interphase FISH with
integration of conventional karyotyping revealed genomic complexity that helped
identification of biological subclasses with clinical impact at diagnosis.
Further, these cytogenetic subclasses along with molecular markers are likely
to evolve more refined prognostic groups, which will help design risk-adapted
therapies in B-CLL.